Yesterday left Reading for my weekly get out of Reading trip. I took the
GWR▸ Paddington stopper to Slough.
Leaving Reading on the northernmost of the lines (presumably not the Up Relief) you cross Kennet mouth, where it joins the Thames, pass the new Park and Ride car park and get to the business park. The first area is Oracle and in their car park is what looked to me like a railway carriage next to a canopy. Google
https://maps.app.goo.gl/njhfgSxMe2pq5dYW9 suggests there is also a length of track.
Usual what and why questions. Apologies if it has all been done before.